Freda Haffner Kettlehole State Preserve

Freda Haffner Kettlehole is a 110-acre preserve containing the largest glacial “kettlehole” in Iowa, created by the melting of a block of glacial ice some 13,000 years ago. A highly diverse native prairie community is also found here. It is located 2 miles west of West Okoboji Lake, approximately 4.5 miles northwest of Milford in Dick­inson County. 

Once known as “Arend’s Kettle Hole” and the “Big Kettle,” the first 12.4 acres were given to the Iowa chapter of The Nature Conservancy in 1972 by local conservationist Freda Haffner. The area was dedicated as a biological and geological state preserve in 1976. 

Directions

1. From the intersection of Highway 71 and Highway 86 north of Milford, take Highway 86 west for 1.5 miles to 210th Street (where Highway 86 curves to the north). 
2. Turn west (left) onto 210th Street and go 2 miles to the parking area for the preserve on the north side of the road (sign: Freda Haffner Kettlehole).

Geological & Topographical Features

The preserve sits on a broad alluvial terrace adjacent to the Little Sioux River valley. It is part of a regional band of “knob and kettle” topography that is distinctive of the terrain formed around the margins of the Bemis and Altamont ice advances of the Des Moines Lobe landform region some 13,000 to 14,000 years ago. Large blocks of ice were carried by the swiftly flowing glacial meltwater. Freda Haffner Kettlehole is the resulting depression left after the partially buried glacial ice melted; it is the largest glacial kettle in Iowa. The kettlehole is about 500 feet across and about 30 feet deep. The kettlehole habitat has a rich flora and fauna that extends from the marshy interior pool, up the steep-sided slopes to the dry gravelly rim of the kettle. 

Flora & Fauna

The preserve supports a flora of over 360 vascular plants, plus thirtyfour bryo­phytes (mosses and liverworts) and numerous lichens. This plant diversity reflects the presence of several habitats ranging from a wetland in the center of the kettle to very dry, gravelly ridges around its rim. 

The marsh in the kettle contains numerous wetland plants. The water is very soft (low in dissolved minerals) and supports high populations of desmids, along with duckweed, naiad, pondweeds, and coontail. The wet marsh edges have American manna grass, rice cut grass, and prairie cordgrass, bulrushes, sedges, spikerushes, broad-leaved arrowhead, burreed, and hornwort. 

The surrounding wet meadow is home to many wet prairie species. Meadow voles, western painted turtles, muskrats, and masked shrew can be found in the lower part of the kettle as well as the rare dion skipper.

The mesic tallgrass prairie species that can be found on the steep slopes include big bluestem, porcupine grass, sideoats grama, switchgrass, and ticklegrass, the forbs Canada goldenrod, tall cinquefoil, New Jersey tea, false boneset, golden alex­anders, wood lily, and wild rose. American toad, northern leopard frog, northern prairie skink, and short-tailed shrew inhabit the mesic hillsides as well as red-winged blackbird and common yellowthroat. 

The dry ridges around the kettlehole have a great diversity of plants. This community is characterized by little bluestem, blue grama, hairy grama, sideoats grama, prairie dropseed, Junegrass, plains muhly, porcupine grass, Missouri goldenrod, Lambert’s crazyweed, and groundplum. 

Along the rim surrounding the kettle, large piles of freshly excavated soil can be found, evidence of the plains pocket gopher. Plains garter snake, badger, and deer mouse also are found on the upland hills, in addition to several butterflies, including the Poweshiek skipperling, Ottoe skipper, Arogos skipper, checkered white, and regal fritillary. 

Hunting is not permitted. 

Other state preserves in the vicinity include Cayler Prairie, Silver Lake Fen, Cheever Lake, and Anderson Prairie.